Transposon tagging of tobacco mosaic virus resistance gene N: its possible role in the TMV-N-mediated signal transduction pathway.

Plants can recognize and resist invading pathogens by signaling the induction of rapid defense responses. Often these responses are mediated by single dominant resistance genes (R genes). The products of R genes have been postulated to recognize the pathogen and trigger rapid host defense responses. Here we describe isolation of the classical resistance gene N of tobacco that mediates resistance to the well-characterized pathogen tobacco mosaic virus (TMV). The N gene was isolated by transposon tagging using the maize Activator (Ac) transposon. We confirmed isolation of the N gene by complementation of the TMV-sensitive phenotype with a genomic DNA fragment. Sequence analysis of the N gene shows that it encodes a protein with an amino-terminal domain similar to that of the cytoplasmic domains of the Drosophila Toll protein and the interleukin 1 receptor in mammals, a putative nucleotide-binding site and 14 imperfect leucine-rich repeats. The presence of these functional domains in the predicted N gene product is consistent with the hypothesis that the N resistance gene functions in a signal transduction pathway. Similarities of N to Toll and the interleukin 1 receptor suggest a similar signaling mechanism leading to rapid gene induction and TMV resistance.

TGA/FTIR study of tobacco and glycerol–tobacco mixtures

In this work, the evolution with temperature of the qualitative composition of the gases evolved in the pyrolysis of glycerol, tobacco and tobacco–glycerol mixtures has been studied. The pathways for different types of compounds (i.e., water, CO, CO2, carbonylic compounds, alkenyl or alkyl groups containing compounds, alcohols and phenols and aromatic compounds) have been established, and their relationship with the different reaction steps involved in the pyrolysis process have been suggested. The comparison among the behavior observed in the pyrolysis of tobacco, glycerol and a mixture glycerol–tobacco has permitted us to suggest possible interactions between tobacco and glycerol affecting the composition of the gases evolved.

Tobacco and its use in Africa / by Berthold Laufer, Wilfrid D. Hambly, and Ralph Linton; 6 plates in photogravure.

no.29(1930)

Introduction of tobacco into Europe / by Berthold Laufer, Curator of Anthropology.

no.19(1924)